Reducing case capacity

[Cast_outlaw]

Ok so looking for some input I was thinking of a way to reduce case capacity to make light boolit loads with to reduce charge size but retain velocity. So what I have done is filled a 303british case with zinc, drilled out the flashole with a 5/64 bit and, down the neck with a 7/32. was going to use the lee 314-90 swc and start around 1.5gr tightgroup. If this sound like a terrible idea and bound for disaster I’ll like to here it or any other opinions.

[cwtebay]

How do you fill the case with zinc? If molten when it's put in I would be very concerned about base annealing the brass. Someone much smarter than me will know if the zinc will deform enough during firing to create extraction or resizing problems also.
On the flip side - definitely an interesting experiment!

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[Rcmaveric]

I wouldnt change case capacity. That will drastically alter your internal ballistics.

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[WebMonkey]

how about a chamber adapter and shoot .32 acp ?

[Texas by God]

It seems to me to be lots of work for little return. Exploring new frontiers perhaps, probably safe enough to try.

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[Cast_outlaw]

I’ll have to double check but I think 32acp is prohibited in Canada so I’m not sure that is an option

[cwtebay]

I’ll have to double check but I think 32acp is prohibited in Canada so I’m not sure that is an option

Webmonkey beat me to the chamber adapter.
I collected them for a while, have a 303 Brit to 32 ACP and 303 to 32 S&W.

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[Scrounge]

How do you fill the case with zinc? If molten when it's put in I would be very concerned about base annealing the brass. Someone much smarter than me will know if the zinc will deform enough during firing to create extraction or resizing problems also.
On the flip side - definitely an interesting experiment!

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I wouldn't worry so much about it annealing the case. More like destroying the alloy of the case by either leaching zinc from it, or adding more zine to it, or both in uncontrolled places. Cartridge brass is about 70/30 copper to zinc, to get the properies they want. It's supposed to be flexible enough to seal the breach, without being too soft, or too brittle. If you HAVE to change the internal volume of the case, I'd make a case with the volume you want, and thicker side-walls. Then try it very carefully to see that it isn't too rigid to seal. Or just make chamber adapters as another poster suggested. I'm wanting to find low-power, or mouse fart/cat sneeze, loads for my 30-06. I've considered chamber adapters to take .30 carbine rounds, but those aren't low power enough. Just a clumsy way to shoot .30 carbine, rather than the low power I'm looking for. For what you want, something like that might be just right, though.

[cwtebay]

I wouldn't worry so much about it annealing the case. More like destroying the alloy of the case by either leaching zinc from it, or adding more zine to it, or both in uncontrolled places. Cartridge brass is about 70/30 copper to zinc, to get the properies they want. It's supposed to be flexible enough to seal the breach, without being too soft, or too brittle. If you HAVE to change the internal volume of the case, I'd make a case with the volume you want, and thicker side-walls. Then try it very carefully to see that it isn't too rigid to seal. Or just make chamber adapters as another poster suggested. I'm wanting to find low-power, or mouse fart/cat sneeze, loads for my 30-06. I've considered chamber adapters to take .30 carbine rounds, but those aren't low power enough. Just a clumsy way to shoot .30 carbine, rather than the low power I'm looking for. For what you want, something like that might be just right, though.

Thank you for elaborating!
As stated above, there are 32 ACP and 32 S & W adapters available for that.
My family and I actually use these fairly frequently, 30-40 Krag, 35 WCF, 303 Brit, 30-06 and 405 WCF are definitely small game / grouse rifles with the adapter. Also a lot of fun!

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[Bazoo]

In the art of bullet casting book, there is an article where it outlines reducing case capacity by inserting a 223 case in a 308 case.

They open the 308 case mouth up, trim a 223 case straight wall to fit to the bottom of the shoulder, Insert it, and reduce the 308 case mouth back to normal.

[cwtebay]

In the art of bullet casting book, there is an article where it outlines reducing case capacity by inserting a 223 case in a 308 case.

They open the 308 case mouth up, trim a 223 case straight wall to fit to the bottom of the shoulder, Insert it, and reduce the 308 case mouth back to normal.

All I can think of when I read that is someone picking that brass up and trying to figure out what the heck happened!!

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[Cast_outlaw]

Well I have one case made up so I’m going to give it a try, and take my hand press with me

[cwtebay]

Well I have one case made up so I’m going to give it a try, and take my hand press with me

Please let us know your results!

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[dverna]

Have you tried 3 gr of Bullseye in a standard case and seeing how it works? Some people will increase the flash hole diameter to get better ignition.

I have some stuff on low level loads for the .30/06, but it is buried somewhere.

Good luck.

[nikonuser]

In the art of bullet casting book, there is an article where it outlines reducing case capacity by inserting a 223 case in a 308 case.

They open the 308 case mouth up, trim a 223 case straight wall to fit to the bottom of the shoulder, Insert it, and reduce the 308 case mouth back to normal.

the amount of wear and tear is not pleasant, and most don't have the ability to remove the mouth of the 308 to start with. However it is safest method.

UNLESS you can lathe turn a piece of cartridge brass rod to the correct outside diameter, THEN bore out a bullet diameter hole from to bottom, then insert a piece of brass tube to become the new neck

[country gent]

Back in the day the govt used a cardboard tube to reduce 45-70 case capacity. It did work.

In Bazoos post here I think I would first open the flash hole to small primer size in the 223 and trim so about .100 longer than body shoulder junction, This way when reforming the 30 cal neck and shoulder a part of the 223 case would be formed to wedge the case in place. Holding it back against the case. In my mind this would give a smoother flow for the primers flash and when dropping powder.

With zincs melting temp of around 900* you are liable to anneal the case head ( with light loads not sure if it will make a big difference), brass anneals around 700* so..... Another concern would be the insert loosing and moving around. A change in the filler will do away with the annealing issue. Instead of zinc use cero safe. Its melting point is under 200*. Hered a pound of cero safe would go a long ways and wouldnt be overly expensive. Or an epoxy in well cleaned cases. Mix a measure amount of epoxy and pour it in the case let harden and drill it. Or turn up a group of rods with a .055 stem 45* shoulder and long enough to get hold of. coat these with several coats of release agent and push thru epoxy and let harden. A bullet dia shaft and the pin angle will center them up nicely. Here you might even consider a tapered shaft ( .100 at pin end to bullet dia 1-1 1/4" up. this would leave a heavier base and a formed charge.

Last will be a way of marking these cases so they dont get mixed in with standard cases. Maybe stamp a L behind the cal designation On the head stamp.

[Gamsek]

Maybe not totally what you want but I had good luck with this extremely well made and of course not cheep cases from Germany for my 7x64

https://samereier.de/samereier---reduzierhülsen.html





I still have them but for all reduced loads I now follow and use this


Good luck!

[303Guy]

I reduced the case capacity of one 303 Brit case using epoxy putty and drilling out the center. I left a seating shoulder at the base of the neck. It worked fine with low pressure loads but when I upped the pressure, the epoxy began to erode.

I did consider fitting a brass tube in the case using an epoxy resin to fill between the tube and the case. That would mean filling the case with resin, inserting the tube, holding it in place until the resin sets then drilling out the resin from inside the tube. That would eliminate the flame erosion problem.

But in the end, I then just went for case fillers, trailboss or bullseye.

[cwtebay]

Maybe not totally what you want but I had good luck with this extremely well made and of course not cheep cases from Germany for my 7x64

https://samereier.de/samereier---reduzierhülsen.html





I still have them but for all reduced loads I now follow and use this


Good luck!

Now that's cool!!! Thank you for sharing this!

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[JohnChrysostom]

Sheesh Germany makes the best stuff, I'd buy those just to make Screwdriver handles & picks out of LOL